Display device

ABSTRACT

To provide a display device capable of reducing in cost more than a conventional device. The invention is a display device including: a display panel; plural first semiconductor chips mounted on the periphery of a first side of a substrate forming the display panel in a first direction; and a first power source wiring layer provided on the periphery of the first side of the substrate, wherein a location of a bump electrode of the first semiconductor chip provided on one end in the first direction, the bump electrode connected to the first power source wiring layer, is different from a location of a bump electrode of the first semiconductor chip provided on the other end in the first direction, the bump electrode connected to the first power source wiring layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application No. 2005-373649 filed onDec. 27, 2005 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to a display device, particularly, atechnology effective in application to a display device in a system thata digital signal is transferred between driving circuits.

2. Description of Related Arts

A TFT (thin film transistor) type liquid crystal display module iswidely used as a display device for a notebook personal computer andsuch. The liquid crystal display module comprises a liquid crystaldisplay panel formed by holding a liquid layer between two transparentsubstrates different in size and a driving circuit for driving theliquid crystal display panel.

As such a liquid crystal display module, known has been one in a systemthat a digital signal (display data or a clock, for example) is inputtedonly to the top of the cascaded driving circuits while a digital signalpasses through driving circuits to be sequentially transferred to theother driving circuits (referred to as a digital signal sequentialtransfer system), as described in Japanese Patent Laid-open No. Hei06-13724 (Patent Reference 1), for example.

In the liquid crystal display device described in Patent Reference 1, asemiconductor integrated circuit device (IC) forming a driving circuitis directly mounted to a transparent substrate (a glassboard, forexample) forming the liquid crystal display panel. A power sourcevoltage for each of gate drivers is supplied from a power source circuitthrough power source wiring provided on a substrate of the liquidcrystal display panel.

In the case of supplying the power source wiring on the transparentsubstrate forming the liquid crystal display panel with current onlyfrom one side, the larger the size of the liquid crystal display panelis, the more the resistance of the power source wiring on thetransparent substrate forming the liquid crystal display panelincreases. For example, a fall of the voltage due to the resistance ofthe power source wiring causes unevenness of the power source voltagesupplied to each gate driver.

The unevenness of the supplied power source voltage in the respectivegate drivers causes a change in on-resistance of a thin film transistor(TFT), and thereby, unevenness of an image voltage written in each pixelelectrode (ITO 1), so that unevenness in display occurs.

Accordingly, in the case of a liquid crystal display panel as large asor more than 12.1 inches in dimension, electric current is fed to thepower source wiring on the transparent substrate forming the liquidcrystal display panel from the both sides, using a circuit board, tostabilize a power source voltage supplied to each gate driver.

On the other hand, there has been a problem that the liquid crystaldisplay module is largely required to be lowered in cost while theliquid crystal display module using the above-mentioned digital signalsequential transfer system is difficult to be further lowered in costsince a circuit board is expensive.

The invention is to solve the problems in the conventional technology.An object of the invention is to provide a technology enabling the costof a display device to be reduced more than the conventional one.

The above-mentioned and other objects and new characteristics of theinvention will be disclosed on the basis of the description and attacheddrawings of the specification.

SUMMARY

Brief description of an outline of represented parts of the inventiondisclosed in the application is as follows.

(1) A display device comprises a display panel; plural firstsemiconductor chips mounted on the periphery of a first side of asubstrate forming the display panel in a first direction; and a firstpower source wiring layer provided on the periphery of the first side ofthe substrate, and in the display device, a location of a bump electrodeof the first semiconductor chip provided on one end in the firstdirection, the bump electrode connected to the first power source wiringlayer, is different from a location of a bump electrode of the firstsemiconductor chip provided on the other end in the first direction, thebump electrode connected to the first power source wiring layer.

(2) The display device according to (1) further comprises: plural secondsemiconductor chips mounted on the periphery of a second side adjacentto the first side of a substrate forming the display panel in a seconddirection; and a second power source wiring layer provided on theperiphery of the second side of the substrate, and in the displaydevice, a location of a bump electrode of the second semiconductor chipprovided on one end in the second direction, the bump electrodeconnected to the second power source wiring layer, is different from alocation of a bump electrode of the second semiconductor chip providedon the other end in the second direction, the bump electrode connectedto the second power source wiring layer.

(3) In the display device according to (1) or (2), the respectivesemiconductor chips comprise: an inner power source wiring layer; pluralbump electrodes connected to the inner power source wiring layer; andplural resistance layers provided between the inner power source wiringlayer and the respective bump electrodes wherein the plural resistancelayers include at least two resistance layers having differentresistance values.

(4) The display device according to any one of (1) to (3) furthercomprises a power source circuit, and in the display device, a locationof a bump electrode of each semiconductor chip, the bump electrodeconnected to the power source wiring layer, is determined in accordancewith a distance from the power source circuit.

(5) In the display device according to any one of (1) to (4), thedisplay panel is 12.1 inches or more in dimension.

(6) In the display device according to any one of (1) to (5), thedisplay panel is a liquid crystal display panel, the fist semiconductorchip is a gate driver and the second semiconductor chip is a draindriver.

An effect achieved by the represented parts of the invention disclosedin the application is briefly described as follows.

In accordance with a display device according to the invention, itbecomes possible to make a reduction in cost more than a conventionaldevice.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements, and wherein:

FIG. 1 illustrates a basic structure of a liquid crystal display moduleusing a digital signal sequential transfer system in accordance with anembodiment of the invention;

FIG. 2 is a sectional view illustrating an inner power source wiringlayer, a resistance layer and a bump electrode of a gate driver inaccordance with an embodiment of the invention; and

FIG. 3 is a block diagram showing a basic structure of a conventionalliquid crystal display module using a digital signal sequential transfersystem.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the invention will be described in detail hereinafter,made reference to drawings.

In all the drawings illustrating the embodiment, what has the samefunction is marked with the same signs and numerals and repeateddescription thereof will be omitted.

[Liquid Crystal Display Module in a Digital Signal Sequential TransferSystem Prerequisite to the Invention]

First, described will be a liquid crystal display module in a digitalsignal sequential transfer system prerequisite to the invention.

FIG. 3 is a block diagram showing a basic structure of a conventionalliquid crystal display module using the digital signal sequentialtransfer system.

In order to form a liquid crystal display panel 100, the TFT substrateon which a pixel element ITO1, a thin film transistor (TFT) and such areformed and a filter substrate on which an opposite electrode, a colorfilter and such are formed are superimposed with a predeterminedinterval therebetween to be stuck on each other by means of a sealingmember provided in the shape of a frame in the vicinity of acircumferential edge between the both substrates, liquid crystal is putto the inside of the sealing member between the both substrates from aliquid crystal enclosing entrance provided at a part of the sealingmember to be enclosed and polarizers are stuck on the outsides of theboth substrates.

Each sub pixel includes a pixel electrode ITO1 and a thin filmtransistor (TFT) and is provided so as to correspond to a part whereplural scanning lines (or gate lines) G and an image line (or a drainline, a source line) D intersect each other.

In an example shown in FIG. 3, holding capacity CST is provided forevery picture for the purpose of holding a potential of the pixelelectrode ITO 1. CL denotes a capacity line for supplying the holdingcapacity CST with a reference voltage Vcom.

Further, in FIG. 3, shown is only one pixel electrode ITO1. The pixelelectrode ITO1, the thin film transistor (TFT) and the holding capacityCST, however, are provided in plural numbers into the shape of a matrix.A scanning line G of a preceding line may be substituted for thecapacity line CL.

A source of the thin film transistor (TFT) of each pixel is connected tothe pixel electrode ITO1. A drain of the same is connected to the imageline D. Agate of the same is connected to the scanning line g. The thinfilm transistor (TFT) functions as a switch for supplying the pixelelectrode ITO1 with a display voltage (a gray scale voltage).

In the conventional liquid crystal display module shown in FIG. 3, adrain driver 130 and a gate driver 140 are mounted on the periphery oftwo sides of a substrate (a glass board, for example) forming the TFTsubstrate of a liquid crystal display panel 100 (SUB 1), respectively.

A power source circuit 110 and a timing controller 120 are respectivelymounted on a circuit board 150 provided on the periphery of the liquidcrystal display panel 100.

The timing controller 120 is formed from one semiconductor integratedcircuit (LSI) to control and drive the drain driver 130 and the gatedriver 140 on the basis of respective display controlling signals of aclock signal, a display timing signal, a horizontally synchronizingsignal and a vertically synchronizing signal and display data (R, G andB), which are sent from a main body side of a computer.

A digital signal (such as display data and a clock signal) 132 sent fromthe timing controller 120 and a gray scale reference voltage 133supplied from the power source circuit 110 are inputted to the top draindriver 130 through a flexible printed wiring board (simply referred toas a FPC substrate, hereinafter) (FPCD), and then, transmitted throughan inner signal line in each drain driver 130 and a transmittance linepath between the respective drain drivers 130 (a wiring layer on a glassboard) to be inputted to each drain driver 130.

Further, a power source voltage of each drain driver 130 is suppliedfrom the power source circuit 110 through a supply line 131 on a FPCsubstrate (FPCS), respectively.

Similarly, a digital signal (such as a clock) 141 sent from the timingcontroller 120 is inputted to the top gate driver 140 through the FPCsubstrate (FPCD), and then, transmitted through an inner signal line ineach gate driver 140 and a transmittance line path between therespective gate drivers 140 (a wiring layer on a glass board) to beinputted to each gate driver 140.

A power source voltage of each gate driver 140 is supplied from thepower source circuit 110 through a power source wiring 142 on asubstrate of the liquid crystal display panel 100.

In FIG. 3, a FPC substrate (FPCG) is provided and the both ends of thepower source wiring 142 on the transparent substrate forming the liquidcrystal display panel 100 are connected to the power source circuit 110so as to feed current from the both sides of the power source wiring 142in order to stabilize the power source voltage supplied to each gatedriver 140.

A basic structure of the liquid crystal display module in accordancewith the embodiment of the invention is same as that of the conventionalliquid crystal display module shown in FIG. 3.

FIG. 2 is a sectional view illustrating an inner power source wiringlayer, a resistance layer and a bump electrode of the gate driver 140 inthe embodiment.

As shown in FIG. 2, in the gate driver 140 in the embodiment, providedare plural bump electrodes (10 bump electrodes in FIG. 2) 302 connectedto an inner power source wiring layer 300 while plural resistance layers301 are provided between the inner power source wiring layer 300 and therespective bump electrodes 302.

The resistance layer 301 is formed so as to include at least tworesistance layers having different resistance values. FIG. 2 shows acase that the resistance layer 301 is formed from three resistancelayers having a resistance value R0, a resistance value Ra and aresistance value Rb (wherein R0<Ra<Rb).

FIG. 1 illustrates a basic structure of a liquid crystal display moduleusing the digital signal sequential transfer system in the embodiment.

As shown in FIG. 1, in the embodiment, used is the gate driver 140illustrated in FIG. 2 to properly select the bump electrode 302 of thegate driver 140, which is connected to a power source wiring 142 on asubstrate of the liquid crystal display panel 100. This allows a voltagevalue of a power source voltage supplied to each drain driver 140 to bean almost same voltage value even in the case of feeding current onlyfrom one side to the power source wiring 142 on a substrate of theliquid crystal display panel 100.

In FIG. 1, in a gate driver 140 a located farthest from the power sourcecircuit 110, the power source wiring 142 on a substrate of the liquidcrystal display panel 100 is connected to the bump electrode 302connected to the resistance layer 301 having the lowest resistance valueR0, as shown by A.

In a gate driver 140 c located nearest to the power source circuit 110,the power source wiring 142 on a substrate of the liquid crystal displaypanel 100 is connected to the bump electrode 302 connected to theresistance layers 301 having the resistance values Ra and Rb.

Furthermore, in a middle gate driver 140 b, the power source wiring 142on a substrate of the liquid crystal display panel 100 is connected tothe bump electrode 302 connected to the resistance layer 301 having thesecond lowest resistance value Ra.

That is to say, in the embodiment, the bump electrode 302 of each gatedriver 140 is selected so that a fall in voltage obtained by adding afall in voltage due to wiring resistance of the power source wiring 142and a fall in voltage due to the resistance layer 301 of each gatedriver 140 would be substantially same in voltage value among therespective gate drivers 140 in the case of feeding current only from oneside to the power source wiring 142 on a substrate of the liquid crystaldisplay panel 100.

This allows a voltage value of the power source voltage supplied to theinner power source wiring layer 300 of each gate driver 140 to besubstantially same even when the power source voltage supplied to eachgate driver 140 is made uneven because of a fall in voltage due towiring resistance of the power source wiring 142 in the case of feedingcurrent only from one side to the power source wiring 142 on a substrateof the liquid crystal display panel 100.

Accordingly, unevenness in display, which is caused by unevenness inpower source voltage supplied to each gate driver 140, can be preventedin the embodiment.

This makes feeding of current from the both sides unnecessary, andthereby, the FPC substrate (FPCG) unnecessary as shown by a broken linein FIG. 1 in the embodiment. Moreover, a circuit board 150 can bereduced in dimension, as shown by an arrow B and the broken line in FIG.1, so that the cost can be reduced.

In the above description, described is a case that plural resistancelayers 301 are provided between the inner part power source wiring layer300 and the respective bump electrodes 302 in the gate driver 140 tosupply the gate driver 140 with a power source voltage by feedingcurrent from one side to the power source wiring 142 on a substrate ofthe liquid crystal display panel 100. The invention, however, is notlimited to the above. It may be arranged that plural resistance layer beprovided between the inner power source wiring layer and the respectivebump electrodes in the drain driver 130 to supply the drain driver 130with a power source voltage by feeding current from one side to thepower source wiring on a substrate of the liquid crystal display panel100.

Further, in the above description, described is an embodiment in whichthe invention is applied to a liquid crystal display device. Theinvention, however, is not limited to the above. The invention may beapplied to an organic electroluminescent display device and the like.

The invention by the present inventor has been concretely describedabove on the basis of the embodiment. It is obvious, of course, however,that the invention is not limited to the above embodiment and may bevariously modified within a range not deviating from the spirit of theinvention.

Moreover, in a different point of view of the invention, picked out canbe the following aspects of the invention.

The invention in the different point of view is a display devicecomprising: a display panel; and a circuit board provided with a powersource circuit for supplying the display panel with a power sourcevoltage, wherein the display panel has a display area as large as ormore than 12.1 inches in dimension, plural gate drivers for controllinga drive of a gate of the display panel are provided on one side on asubstrate forming the display panel so as to be aligned in accordancewith a COG method, a supply line for supplying each of the plural gatedrivers with a power source voltage from the power source circuit isprovided on the substrate along the plural gate drivers and the supplyline and the circuit board are connected on one side of the supply linethrough one flexible printed board.

Such a structure allows one-side current feeding of a power sourcevoltage to a gate driver, which has been conventionally impossible inthe case of a display area as large as or more than 12.1 inches indimension, to be achieved, and thereby, the circuit board to be madesmall in dimension, so that a low-cast display device can be provided.

The display device has an effect of the invention so long as it includesthree or more gate drivers. This means that, although the invention iseffective, of course, even for a structure in which two gate drivers areprovided, the more the number of the gate driver is, the more theinvention is effective in the case of a display area as large as or morethan 12.1 in dimension, 17 inches, for example, or a further largerdisplay area such that the gate drivers fewer in number areinsufficient.

In addition, in the display device, a location of an electrode of a gatedriver nearest among the plural gate drivers to a side on which theflexible printed board is provided, the electrode connected to thesupply line, is different from a location of an electrode of a gatedriver farthest among the plural gate drivers from the side on which theflexible printed board is provided, the electrode connected to thesupply line. This means that locations of electrodes of at least thegate drivers on the both ends are different and that a location of anelectrode of the gate driver provided in the middle part is also changedin accordance with necessity.

In this aspect of the invention, the display device is also applicableto an organic electroluminescent device and such other than the liquidcrystal display device.

1. A display device comprising: a display panel; plural firstsemiconductor chips mounted on the periphery of a first side of asubstrate forming the display panel in a first direction; and a firstpower source wiring layer provided on the periphery of the first side ofthe substrate, wherein a location of a bump electrode of the firstsemiconductor chip provided on one end in the first direction, the bumpelectrode connected to the first power source wiring layer, is differentfrom a location of a bump electrode of the first semiconductor chipprovided on the other end in the first direction, the bump electrodeconnected to the first power source wiring layer.
 2. The display deviceaccording to claim 1, further comprising: plural second semiconductorchips mounted on the periphery of a second side adjacent to the firstside of a substrate forming the display panel in a second direction; anda second power source wiring layer provided on the periphery of thesecond side of the substrate, wherein a location of a bump electrode ofthe second semiconductor chip provided on one end in the seconddirection, the bump electrode connected to the second power sourcewiring layer, is different from a location of a bump electrode of thesecond semiconductor chip provided on the other end in the seconddirection, the bump electrode connected to the second power sourcewiring layer.
 3. The display device according to claim 1, wherein therespective semiconductor chips comprise: an inner power source wiringlayer; plural bump electrodes connected to the inner power source wiringlayer; and plural resistance layers provided between the inner powersource wiring layer and the respective bump electrodes, wherein theplural resistance layers include at least two resistance layers havingdifferent resistance values.
 4. The display device according to claim 1,further comprising: a power source circuit, wherein a location of a bumpelectrode of each semiconductor chip, the bump electrode connected tothe power source wiring layer, is determined in accordance with adistance from the power source circuit.
 5. The display device accordingto claim 1, wherein the display panel is 12.1 inches or more indimension.
 6. The display device according to claim 1, wherein thedisplay panel is a liquid crystal display panel.
 7. The display deviceaccording to claim 6, wherein the fist semiconductor chip is a gatedriver and the second semiconductor chip is a drain driver.
 8. A displaydevice comprising: a display panel; and a circuit board provided with apower source circuit for supplying the display panel with a power sourcevoltage, wherein the display panel has a display area as large as ormore than 12.1 inches in dimension, plural gate drivers for controllinga drive of a gate of the display panel are provided on one side on asubstrate forming the display panel so as to be aligned in accordancewith a COG method, a supply line for supplying each of the plural gatedrivers with a power source voltage from the power source circuit isprovided on the substrate along the plural gate drivers and the supplyline and the circuit board are connected on one side of the supply linethrough one flexible printed board.
 9. The display device according toclaim 8, wherein the gate driver is three or more in number.
 10. Thedisplay device according to claim 9, wherein a location of an electrodeof a gate driver nearest among the plural gate drivers to a side thatthe flexible printed board is provided on, the electrode connected tothe supply line, is different from a location of an electrode of a gatedriver farthest among the plural gate drivers from the side that theflexible printed board is provided on, the electrode connected to thesupply line.
 11. The display device according to claim 8, wherein thedisplay panel is a liquid crystal display panel.